阅读说明：本技术 一种多点低慢小空中目标跟踪临视系统 (Multi-point low-slow small aerial target tracking sighting system ) 是由 范世铭 朱圣棋 陈刚毅 王喜进 范林秀 于 2019-11-04 设计创作，主要内容包括：本发明涉及雷达低空目标跟踪技术领域,具体涉及一种多点低慢小空中目标跟踪临视系统,采用如下步骤：步骤一：构建相控阵雷达的坐标系；步骤二：跟踪滤波坐标系的选择；步骤三：低空目标的状态方程,步骤四：建立目标观测模型和状态模型；步骤五：相关多径误差的去相关过程；步骤六：应用交互多模算法；它根据低空目标的观测噪声的特性,建立两个模型；计算仿真结果表明,算法有效地利用了两个模型,在多径误差出现尖峰的时间点上,自动地增大观测方程中观测噪声的方差,减弱了多径误差的影响,提高了跟踪性能。(The invention relates to the technical field of radar low-altitude target tracking, in particular to a multi-point low-speed small-altitude target tracking sighting system, which adopts the following steps: the method comprises the following steps: constructing a coordinate system of the phased array radar; step two: selecting a tracking filtering coordinate system; step three: the equation of state of the low-altitude target, step four: establishing a target observation model and a state model; step five: a decorrelation process of the correlated multipath error; step six: applying an interactive multi-modal algorithm; according to the characteristics of observation noise of a low-altitude target, two models are established; the calculation simulation result shows that the algorithm effectively utilizes the two models, automatically increases the variance of observation noise in the observation equation at the time point when the multipath error has a peak, weakens the influence of the multipath error and improves the tracking performance.)

1. A multi-point low-slow small aerial target tracking sighting system is characterized in that: the method comprises the following steps:

the method comprises the following steps: the method comprises the following steps of (1) constructing a coordinate system of the phased array radar:

(1) establishing a rectangular coordinate system OXYZ with the radar as the center;

(2) establishing a phased array radar based phased array coordinate system OX_rY_rZ_r；

(3) Phase matrix coordinate system OX_rY_rZ_rIs obtained by rotating a rectangular coordinate system OXYZ;

step two: and selecting a tracking filter coordinate system by adopting the following steps:

(1) the phased array radar measures the distance R, the pitch angle theta and the azimuth angle alpha of a target, the coordinate of the target in a rectangular coordinate system is (x, y, z), and a coordinate conversion formula is providedAnd (3) rotating operation:

(2) selecting two filters, wherein one filter is used for mutually coupled x and y coordinates, the other filter is used for a z coordinate, and a corresponding multipath elimination technology is adopted in the z coordinate direction to inhibit errors caused by multipath propagation;

step three: the state equation of the low-altitude target adopts the following steps:

(1) the target has a normal level, and the measurement and state equation of the height is:

x(k+1)＝x(k)+Tv(k+1)

z(k)＝x(k)+w(k)

wherein x (k), z (k) represent the true and measured height of the target, w (k) is the measurement noise of white gauss, and v (k) represents the vertical velocity of the target; the noise is white Gaussian noise caused by vibration factors of the earth curved surface or the height of a target;

(2) process noise variance σ_v ²Can be selected according to the maximum speed at which the target is maneuvering, σ_vShould be related to the maximum vertical velocity

Step four: establishing a target observation model and a state model:

observation model 1: z (k) ═ x (k) + w (k), observation model 2: z (k) ═ x (k) + w_M(k)；

Wherein: w is a_MThe observation noise caused by multipath is an autocorrelation sequence and can be generated by a first-order AR model;

w_M(k)＝αw_M(k-1)+v_M；

wherein: α is an AR model parameter, v_MIs zero mean self-noise in AR model with variance of sigma_vM ²；

Step five: the decorrelation process of the correlated multipath error adopts the following steps:

(1) the noise in the observation model 2 in the step four has autocorrelation, and a Kalman filtering algorithm cannot be directly adopted; to decorrelate the observation noise, the sum of the observations at the current time is multiplied by a weighting factorThe observation of the previous moment in time of (c) yields a new sequence:

if it is

The last term on the right side of the above equation is usually small and can be ignored, then there is

Autocorrelation sequence w_MThe autocorrelation function of (a) is r (k),

(2) the above correlation function can be estimated recursively as follows:

the noise sequence in the above equation can be generated by:

step six: applying an interactive multi-modal algorithm, comprising the steps of:

(1) as described in the above steps, there are two possible observation models, filtering needs to mix two system state estimators, and an interactive multimode algorithm is applied to obtain a final state estimation;

(2) the system assumes one of two models,

M(k)∈{M₁,M₂in which M is₁For multipath-free noise models, M₂A multipath noise model is provided;

(3) markov transition probability of model is u_i,j＝{M_j(k)|M_i(k-1)}，

Indicating that the model is known as M at time k-1_iThe model at time k is M_jHas only two target models, then the state transition matrix is

2. The multi-point low-slow small aerial target tracking sighting system according to claim 1, wherein: in a rectangular coordinate system OXYZ centered on the radar in the first step, Z is upward along the local vertical line, X and Y are located in the local horizontal plane, X is directed to the east, and Y is directed to the north.

3. The multi-point low-slow small aerial target tracking system as claimed in claim 1Face sight system, its characterized in that: the phased array radar in the step one has a phase array coordinate system OX_rY_rZ_rIn, Z_rPerpendicular to the radar plane, upwards, X_rAnd Y_rLocated within the radar array and orthogonal to each other, X_rParallel to the intersection of the radar front and the local horizontal plane.

4. The multi-point low-slow small aerial target tracking sighting system according to claim 1, wherein: in step one, an array coordinate system OX_rY_rZ_rIs obtained by rotating an orthogonal coordinate system OXYZ by taking Z as north axis and clockwise as positive rotation by a lambda angle, and transforming a matrix T₁Obtaining OX ' Y ' Z '; then, the matrix T is transformed by rotating by a phi angle clockwise by taking X' as an axis₂The coordinate system is rotated to OX_rY_rZ_r；

The total transformation matrix T:

[ technical field ] A method for producing a semiconductor device

The invention relates to the technical field of radar low-altitude target tracking, in particular to a multi-point low-speed small-air target tracking sighting system.

[ background of the invention ]

The low-altitude slow-speed small target (hereinafter referred to as "low-speed small") has the characteristics of difficult control, difficult detection and difficult disposal, and is a worldwide problem aiming at low-speed small air defense. The low-slow state refers to a target with the flying height below, the flying speed below and the reflection section below. The low and slow targets in the following airspace are difficult to detect and prevent due to the fact that the low and slow targets are small in size, simple to operate and control, capable of carrying certain heavy objects, low in flying height, much in ground object shielding and incapable of being covered by air force and radar equipment.

The low and slow small targets which can be seen at present comprise more than ten types of aeromodels, power delta wings, power umbrellas, delta wings, paragliders, aerospace models, light and ultra-light airplanes, light helicopters, gliders, hot air airships, hot air balloons, suspension balloons, kites and the like. Wherein the control is difficult, and the model airplane, the power delta wing, the power umbrella, the paraglider and the like which carry leaflets or some dangerous goods are not easy to prevent. The paraglider and the glider have complicated lift-off conditions and limited power parachute access, so that the aviation model has high concealment, easy availability, sudden lift-off, easy control and small reflection section, which becomes the key point and difficulty of prevention and control. The prevention of interference and damage of low-altitude slow-speed small targets in treatment is a worldwide problem of great security activities, and is highlighted as follows: difficult control, detection and disposal.

The invention provides a system and a method for monitoring a low-slow small unmanned aerial vehicle, which are based on the patent with the patent application number of 201710910422.6 and the publication number of CN107577198A, and the invention combines a radar laser range finder, a radar and photoelectric equipment; detection device, leave empty unmanned aerial vehicle can realize discovering and discerning unmanned aerial vehicle's automation, compatible multiple monitoring means to send command control platform through wireless network and carry out data analysis, processing, storage, solved that single discovery mode discovery rate is low and the shortcoming of the condition of failing to police appears easily, improved the discovery rate, reduced the condition of failing to police, improved work efficiency.

However, the above method has a disadvantage in that although it successfully eliminates measurement errors that differ significantly when the monopulse radar and channel signals are small, it cannot eliminate approximately constant deviations that would otherwise exist in the monopulse ratio.

[ summary of the invention ]

The invention aims to provide a multi-point low-speed small aerial target tracking sighting system aiming at the defects and shortcomings of the prior art.

The invention relates to a multi-point low-slow small aerial target tracking sighting system, which adopts the following steps:

the method comprises the following steps: the method comprises the following steps of (1) constructing a coordinate system of the phased array radar:

(1) establishing a rectangular coordinate system OXYZ with the radar as the center;

(2) establishing a phased array radar based phased array coordinate system OX_rY_rZ_r；

(3) Phase matrix coordinate system OX_rY_rZ_rIs obtained by rotating a rectangular coordinate system OX YZ;

step two: and selecting a tracking filter coordinate system by adopting the following steps:

(1) the phased array radar measures the distance R, the pitch angle theta and the azimuth angle alpha of a target, the coordinates of the target in a rectangular coordinate system are (x, y, z), and then the rotating operation of a coordinate conversion formula is performed:

(2) selecting two filters, wherein one filter is used for mutually coupled x and y coordinates, the other filter is used for a z coordinate, and a corresponding multipath elimination technology is adopted in the z coordinate direction to inhibit errors caused by multipath propagation;

step three: the state equation of the low-altitude target adopts the following steps:

(1) the target has a normal level, and the measurement and state equation of the height is:

x(k+1)＝x(k)+Tv(k+1)

z(k)＝x(k)+w(k)

wherein x (k), z (k) represent the true and measured height of the target, w (k) is the measurement noise of white gauss, and v (k) represents the vertical velocity of the target; the noise is white Gaussian noise caused by vibration factors of the earth curved surface or the height of a target;

(2) process noise variance σ_v ²Can be selected according to the maximum speed at which the target is maneuvering, σ_vShould be related to the maximum vertical velocity

Step four: establishing a target observation model and a state model:

observation model 1: z (k) ═ x (k) + w (k), observation model 2: z (k) ═ x (k) + w_M(k)；

Wherein: w is a_MThe observation noise caused by multipath is an autocorrelation sequence and can be generated by a first-order AR model;

w_M(k)＝αw_M(k-1)+v_M；

wherein: α is an AR model parameter, v_MIs zero mean self-noise in AR model with variance of sigma_vM ²；

Step five: the decorrelation process of the correlated multipath error adopts the following steps:

(1) the noise in the observation model 2 in the step four has autocorrelation, and a Kalman filtering algorithm cannot be directly adopted; to decorrelate the observation noise, the sum of the observations at the current time is multiplied by a weighting factorThe observation of the previous moment in time of (c) yields a new sequence:

if it is

The upper formula is

The last term on the right side of the above equation is usually small and can be ignored, then there is

Autocorrelation sequence w_MThe autocorrelation function of (a) is r (k),

(2) the above correlation function can be estimated recursively as follows:

the noise sequence in the above equation can be generated by:

wherein:estimating a state vector x (k) for the k time in the filtering process;

step six: applying an interactive multi-modal algorithm, comprising the steps of:

(1) as described in the above steps, there are two possible observation models, filtering needs to mix two system state estimators, and an interactive multimode algorithm is applied to obtain a final state estimation;

(2) the system assumes one of two models,

M(k)∈{M₁,M₂in which M is₁For multipath-free noise models, M₂A multipath noise model is provided;

(3) markov transition probability of model is u_i,j＝{M_j(k)|M_i(k-1)}，

Indicating that the model is known as M at time k-1_iThe model at time k is M_jHas only two target models, then the state transition matrix isWherein the model is M at time k-1_iKeeping the model M at time k_iProbability P of_iiSatisfies the following formula:

in the formula T_iAs model M_iT is the sampling interval.

Further, in the rectangular coordinate system OXYZ centered on the radar in the step one, Z is upward along the local vertical line, X and Y are located in the local horizontal plane, X points to the east, and Y points to the north.

Further, the phased array radar in step one has its phased array coordinate system OX_rY_rZ_rIn, Z_rPerpendicular to the radar plane, upwards, X_rAnd Y_rLocated within the radar array and orthogonal to each other, X_rParallel to the intersection of the radar front and the local horizontal plane.

Further, in step one, the phase matrix coordinate system OX_rY_rZ_rIs obtained by rotating a rectangular coordinate system OX YZ by taking Z as north axis and clockwise as positive rotation by a lambda angle to transform a matrix T₁Obtaining OX ' Y ' Z '; then, the matrix T is transformed by rotating by a phi angle clockwise by taking X' as an axis₂The coordinate system is rotated to OX_rY_rZ_r；

The total transformation matrix T:

the invention has the beneficial effects that: the invention relates to a multipoint low-speed small aerial target tracking near-vision system, which establishes two models according to the characteristics of observation noise of a low-altitude target; the calculation simulation result shows that the algorithm effectively utilizes the two models, automatically increases the variance of observation noise in the observation equation at the time point when the multipath error has a peak, weakens the influence of the multipath error and improves the tracking performance.

[ description of the drawings ]

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, and are not to be considered limiting of the invention, in which:

fig. 1 is a schematic diagram of a radar phased array coordinate system and a rectangular coordinate system in the present invention.

[ detailed description ] embodiments

The present invention will now be described in detail with reference to the drawings and specific embodiments, wherein the exemplary embodiments and descriptions are provided only for the purpose of illustrating the present invention and are not to be construed as limiting the present invention.

The invention relates to a target tracking temporary viewing system which is developed aiming at the problems of low altitude and low speed small targets in the background technology, high flying height, more ground feature shielding, incapability of covering by air force and radar equipment, high concealment, easiness in availability, sudden rising, easiness in control, small reflection section, prevention and control key and difficulty, difficulty in control and control, difficulty in detection, difficulty in handling and the like. The invention provides a compensation measure for improving the measurement precision, thereby being capable of restraining the error of multipath propagation in low-altitude target tracking.

The invention aims at the influence of sea clutter and multipath propagation on the detection and tracking of low-altitude targets, and has the characteristic different from that of high-altitude targets. The experimental radar in the design is generally divided into a low-altitude mode and a medium-altitude mode during design, and the low-altitude mode is switched to when a low-altitude target is detected and tracked. In the low-altitude mode, due to errors caused by multipath propagation and maneuvering characteristics of the low-altitude target, the selection of the target tracking filter coordinate system and the target state equation are different. Therefore, in the first step of the method, the coordinate system of the phased array radar is firstly constructed, then the tracking filtering coordinate system is selected, and then the state equation of the low-altitude target is constructed.

In the present invention, the influence of multipath propagation is mainly reflected in the pitch angle direction. Therefore, the present invention focuses on solving the tracking filtering problem in the radar pitch angle direction (in the target height direction). In order to eliminate the error of multipath propagation, a corresponding multipath elimination technology is adopted in the detection and tracking stages of the radar.

The interactive multi-mode algorithm (IMM) related in the invention is firstly proposed by Bar-Shalom et al, and the algorithm adopts a plurality of models with different maneuvering characteristics to comprehensively describe the motion change rule of a target, and the transition mountain Markov process characterization between the models is a better filtering algorithm assumed by multi-models. bar-hSalom and a.kumar apply the algorithm to low-altitude target tracking, and propose a filtering algorithm for tracking low-altitude targets. Two observation models are established in the algorithm and respectively correspond to the observation with weak multipath error influence and strong multipath error influence, wherein the multipath error with autocorrelation is described by an AR model.

The multi-point low-slow small aerial target tracking sighting system of the specific embodiment tracks a low-altitude target by utilizing an IMM algorithm and adopts the following steps:

the method comprises the following steps: as shown in fig. 1, a coordinate system of the phased array radar is constructed by the following steps:

(1) the XYZ is a rectangular coordinate system with a radar as a center;

wherein: z is up along the local vertical, X and Y are located in the local horizontal plane, X points east and Y points north;

(2)OX_rY_rZ_ris the phased array radar's phased array coordinate system;

wherein: z_rPerpendicular to the radar plane, upwards, X_rAnd Y_rLocated within the radar array and orthogonal to each other, X_rThe intersection line of the radar array surface and the local horizontal plane is parallel to;

(3) phase matrix coordinate system OX_rY_rZ_rIs obtained by rotating a rectangular coordinate system OX YZ; the matrix T is transformed by taking Z as north axis and clockwise as positive rotation by a lambda angle₁Obtaining OX ' Y ' Z '; then, the matrix T is transformed by rotating by a phi angle clockwise by taking X' as an axis₂The coordinate system is rotated to OX_rY_rZ_r(ii) a Total transformation matrix T

Step two: and selecting a tracking filter coordinate system by adopting the following steps:

(1) the phased array radar measures the distance R, the pitch angle theta and the azimuth angle alpha of a target, the coordinates of the target in a rectangular coordinate system are (x, y, z), and then the rotating operation of a coordinate conversion formula is performed:

(2) selecting two filters, one filter is used for mutually coupled x and y coordinates, and the other filter is used for a z coordinate; the error caused by multipath propagation is most prominent in the z direction, and the selection also facilitates the adoption of a corresponding multipath elimination technology in the z coordinate direction to inhibit the error caused by multipath propagation;

wherein: the coordinate conversion formula on the x and y planes is as follows:

wherein R is₀＝Rcosα，

Wherein: the error covariance matrix in the x and y directions is:

wherein

Step three: the state equation of the low-altitude target adopts the following steps:

(1) the target has a constant horizontal height, and the height measurement and state equation are as follows:

x(k+1)＝x(k)+Tv(k+1)

z(k)＝x(k)+w(k)

wherein x (k), z (k) represent the true and measured height of the target, w (k) is the measurement noise of white gauss, and v (k) represents the vertical velocity of the target; caused by the factors of the vibration (such as airflow, terrain matching flight and the like) of the earth curved surface or the height of a target, the noise is white Gaussian noise;

(2) process noise variance σ_v ²Can be selected according to the maximum speed at which the target is maneuvering, σ_vShould be related to the maximum vertical velocity

Step four: establishing a target observation model and a state model:

observation model 1: z (k) ═ x (k) + w (k), observation model 2: z (k) ═ x (k) + w_M(k)；

Wherein: w is a_MThe observation noise caused by multipath is an autocorrelation sequence and can be generated by a first-order AR model;

w_M(k)＝αw_M(k-1)+v_M

wherein: α is an AR model parameter, v_MIs zero mean self-noise in AR model with variance of sigma_vM ²；

Step five: the decorrelation process of the correlated multipath error adopts the following steps:

(1) the noise in the observation model 2 in step four has autocorrelation and the Kalman filtering algorithm cannot be directly adopted. To decorrelate the observation noise, the sum of the observations at the current time is multiplied by a weighting factor

The observation of the previous moment in time of (c) yields a new sequence:

if it is

The upper formula is

The last term on the right side of the above equation is usually small and can be ignored, then there is

Autocorrelation sequence w_MThe autocorrelation function of (a) is r (k),

(2) the correlation function can be recursively estimated as follows:

the noise sequence in the above equation can be generated by

The state vector x (k) is estimated for time k in the filtering process.

Step six: applying an interactive multimodal (IMM) algorithm, comprising the steps of:

(1) as described in the above steps, there are two possible observation models, filtering needs to mix two system state estimators, and an interactive multimode algorithm is applied to obtain a final state estimation;

(2) the system assumes one of two models,

M(k)∈{M₁,M₂in which M is₁For multipath-free noise models, M₂A multipath noise model is provided;

(3) markov transition probability of model is u_i,j＝{M_j(k)|M_i(k-1)}，

Indicating that the model is known as M at time k-1_iThe model at time k is M_jHas only two probabilitiesFor each object model, the state transition matrix is

Wherein the model is M at time k-1_iKeeping the model M at time k_iProbability P of_iiSatisfies the following formula:

in the formula T_iAs model M_iT is the sampling interval.

The invention relates to a multipoint low-speed small aerial target tracking near-vision system, which establishes two models according to the characteristics of observation noise of a low-altitude target; the calculation simulation result shows that the algorithm effectively utilizes the two models, automatically increases the variance of observation noise in the observation equation at the time point when the multipath error has a peak, weakens the influence of the multipath error and improves the tracking performance.

The above description is only a preferred embodiment of the present invention, and all equivalent changes or modifications of the structure, characteristics and principles described in the present invention are included in the scope of the present invention.